Juneau officials pick a fight with invasive weed

Garlic mustard, or Alliaria petiolata, is flourishing on the downtown hillside between Distin Avenue and Village Streets, much to the dismay of state, federal, local and tribal officials. They are launching an effort to eradicate the invasive plant before it takes hold elsewhere in Juneau.

Phil Johnson, a computer specialist with Tlingit-Haida Central Council and a naturalist, first spotted an unfamiliar, lone plant near the Alaska Native Brotherhood hall last year. He sent the specimen to The Nature Conservancy, where experts identified it as garlic mustard. It was the first the time plant had been noted officially in Alaska, he said.

"This spring, I saw two seedlings 10 feet away from the original plant," he said. "The original plant was flowering and hadn't gone to seed yet, so I knew the seeds didn't come from that. It's a biennial so this would have been its second year and it dies after that."

Johnson looked around and found the current crop on the hillside behind the ANB Hall. A small team of volunteers carefully pulled about 3,000 plants last weekend, but plenty more remain.

"The further we went back in the hills we just kept on finding it," Johnson said.

True to its name, garlic mustard has an onion smell. Its dark green leaves are kidney-shaped with scalloped edges. A mature plant can grow to 2 1/2 to 3 feet high and produce hundreds of seeds. It isn't poisonous but has been labeled noxious in some states, according to Tom Heutte, a pest management technician with the University of Alaska Cooperative Extension Service in Juneau.

"It has the tendency to exclude other plants, the native species," he said. "It's caused habitat degradation in a number of Eastern and Midwestern states and Canadian provinces."

Garlic mustard is shade-tolerant plant that could impact fish and wildlife habitat, according to Catherine Pohl, a local habitat biologist. A volunteer group that pulled weeds earlier this month in Juneau noticed some of the seed pods in sunnier places were yellowing and starting to dry, she said.

"It's the first one we know of here that might potentially come in and change the understory, particularly of a mixed forest," she said. "Some river corridors would be of concern."

Representatives from the U.S. Forest Service, Tlingit-Haida Central Council, the Cooperative Extension Service and other groups met Thursday to plot strategy. After talking with local property owners, biologists surveyed the area Saturday to map exactly where the plant has sprouted. Volunteers are scheduled to remove the weeds later this month.

"Since we've got it contained, we could actually wipe it out," Heutte said. "That's the potential and that's why we're trying to work fast."

People who think they might have garlic mustard in their yards should leave it alone and call the Cooperative Extension office in Juneau, Heutte said. Officials also are asking people to stay out of the hillside near Distin Avenue and Village Streets to avoid spreading seeds, he said.

"They should call me," he said. "We'll wind up sending a team to your home to pull the weeds for you, which is easier than pulling them yourself. Plus, we need to get information on where it spreads."

Officials aren't sure how garlic mustard got to Juneau. It could have arrived in a seed packet, on the cuff of someone's pants, from a car off the ferry or with a tree from the Lower 48, Heutte said.

Seeds from garlic mustard mostly are spread by water, humans, animals and vehicles, according to information from The Nature Conservancy. To get rid of the plants, the local team will have to pull them by the root and take them to be incinerated. People in the area will need to wash their shoes with water to avoid taking the seeds elsewhere in town.

The group working on the garlic mustard problem plans to monitor the weed's invasion over the next several years and track other invasive species that have been spotted in Juneau such as Japanese knotweed, Heutte said.